The use of water continues to sharply increases as industrial society and life standard advance, as a result of which sewage and wastewater are produced a lot, so the demand on sewage and wastewater disinfection and purification facility increases, and the expansion of purification facility for supplying drinkable water is demanded a lot.
An ordinary water treatment technology is formed of a biological treatment technology using microorganism and a physical and chemical treatment technology such as a filtration, a coagulation, a precipitation or an adsorption; however the construction of the biological treatment technology costs a lot, and it is hard to eliminate a non-biodegradable contamination substance, and the operation of a physical and chemical treatment technology costs a lot as well while producing a lot of sludge.
Chlorine disinfection generally used in an ordinary water treatment plant produces, during treatments, a THM (Trihalomethanes) substance which is harmful to a human body, and it is disadvantageously hard to eliminate chlorine organic compounds which are discharged from a variety of industry sites.
For the above reasons, an ultraviolet light sterilization which is directed to sterilize bacteria and harmful microorganism without producing a secondary contamination receives attention. The ultraviolet light sterilization is directed to performing sterilization by destroying the DNA of microorganism by scanning an ultraviolet light of a wavelength of 253.7 nm to microorganism or inhibiting proliferation operation.
The photocatalyst sterilization method recently receives attention, which method is directed to efficiently eliminating non-biodegradable organic compounds contained in water by treating the wastewater which is hard to treat by a standard active sludge method in such a way to combine and use semiconductor metallic compounds such as ultraviolet light and TiO2. Here, the photocatalyst is directed to a substance which has a catalyst reaction by means of light such as ultraviolet light (UV), thus effectively eliminating contamination substances by oxidizing and degrading various contamination substances which come into contact with. The photocatalyst makes it possible to prevent a secondary contamination in such a way to fully oxidize and degrade the contamination substances while treating contamination substances in their liquid and gaseous phases. It can treat at a room temperature and a normal pressure as well as at a low temperature, and is excellently advantageous in eliminating BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), chromaticity, SS (Settable Solids) and a small elimination function. In addition, its application currently spreads over a variety of industrial fields and actual life such as in the fields of heavy metal elimination, non-biodegradable organic substance elimination, and sterilizations of various microorganisms.
The ultraviolet light sterilization method has a short effective range in terms of ultraviolet light, so a high power ultraviolet light lamp or a plurality of ultraviolet light lamps are needed for the purpose of treating a proper amount of work. FIG. 4 is a view illustrating a ultraviolet light sterilization device with a plurality of ultraviolet light lamps. As shown in FIG. 4, the ordinary ultraviolet light sterilization device comprises a housing 1 with an inlet port 1a and an outlet port 1b at its both sides for passing fluid such as air or water into the interior, and crystal tubes 2 spaced at regular intervals in the interior of the housing 1, the ultraviolet ray lamp 3 being inserted in the interior of the crystal tube. In FIG. 4, reference numeral 4 represents a photocatalyst coating carrier filled around the crystal tubes 2.
The ultraviolet light sterilization device is characterized in that the crystal tubes 2 with the ultraviolet light lamp 3 being inserted into the same are arranged at regular intervals in the interior of the housing 1 for the purpose of ensuring that ultraviolet light can uniformly scan from the ultraviolet light lamp 3. For example, as shown in FIG. 5, in case that the cross section of the housing 1′ is circular, the crystal tubes 2′ are arranged at the regular intervals on the concentric circle around the center and at it surrounding. As shown in FIG. 6, when the cross section of the housing 1″ is rectangular, the crystal tubes 2″ arranged at regular intervals. Here, the regions S1 and S2 (hereinafter referred to “sterilization regions”) where are sterilized as the ultraviolet rays reach from the ultraviolet light lamp inserted in the crystal tubes 2′ and 2″ for effective sterilizations are formed in a circular shape about each crystal tube 2′, 2″. As shown in FIGS. 5 and 6, the crystal tubes 2′ and 2″ are so arranged that the sterilization regions S1 and S2 do not overlapped with each other. In case that the crystal tubes 2′ and 2″ are arranged so that the sterilization regions S1 and S2 do not overlap with each other, the regions where the sterilization regions S1 and S2 do not overlap with each other are formed, in other words, the ultraviolet light scanning dead regions D1 and D2 are formed, so the fluid passing through the ultraviolet light scanning dead regions D1 and D2 is not fully sterilized. The above problems might be resolved by overlapping the sterilization regions S1 and S2, but the unnecessary sterilization is conducted at the portions where the sterilization regions S1 and S2 are overlapped, after the sterilization is fully performed, thus consuming more energy. In case that the crystal tubes 2′ and 2″ are arranged so that the sterilization regions S1 and S2 are overlapped, a lot of crystal tubes 2′ and 2″ are required, so the number of assembling processes increases, so the manufacture costs a lot. In case that photocatalyst is used together with ultraviolet light, it is hard to adjust the amount of ultraviolet light scanned to the photocatalyst coating carrier.